Hyoyeon and Kai were a couple during their high school days. Everyone said they were perfect for each other. Both were great dancers and popular. One day, Hyoyeon asked to meet Kai and she abruptly said that she wanted to break up with him. Then she ran off. Kai tried to catch her, but she ran so fast. Kai had no idea why Hyoyeon wanted to break up because they were such a happy couple. He tried to contact her and went to her house, but got no responses. He also tried to find her at school, but she was nowhere to be found. Turned out, she was no longer a student there and the school staff didn't know where she went. Heartbroken and devastated, Kai vowed to himself to find her, and planned for a little revenge.

2 years later, Kai was accepted as a new student in the nation's most prestigious university. On the orientation day, he accidentally saw a girl looked like Hyoyeon, who was more beautiful than the last time he saw her, most definitely. She was seen giggling with her friends and holding a guy's hand so affectionally. Kai's face fell and he didn't know what to do. Should he keep taking a revenge on her or just let the happy couple together?